Abstract

Because the U.S. West Coast can present hazardous conditions in which to conduct field monitoring studies, new techniques must be developed to aid in data collection. The U.S. Army Corps of Engineers (USACE) Portland District has developed a bathymetry collection system which can operate in high energy wave conditions or dangerous environments inaccessible to other types of survey methods. The new system is capable of traversing steep grades, passing safely through the surf zone, operating on land, over structures, or in water with remarkable accuracy. A marked lead line suspended from a helicopter is used as a survey rod. A survey crew on shore uses a total station and a level to measure and location of the helicopter and the depth of the seabed. The USACE Portland District has been using this system since 1960. In the summer of 1990, this Helicopter-Borne Nearshore Survey System (HBNSS) was compared for accuracy and repeatability to the USACE Coastal Research Amphibious Buggy (CRAB) at the USACE Waterways Experiment Station, Coastal Engineering Research Center (CERC) Field Research Facility in Duck, North Carolina.